(a) Field of the Invention
This invention relates to exopolysaccharide delivery system of active molecules into a patient and/or increase the activity of the active molecules.
(b) Description of Prior Art
Encapsulation of bioactive compounds in natural or synthetic matrices has been extensively studied over the past decades. Advantages of encapsulation are numerous. Firstly, it provides protection from the inactivation or degradation of the bioactive compound. Secondly, it controls the kinetics of compound release, allowing the optimization of the blood concentration profile. Thirdly, it can also improve therapeutic indices of bioactive compounds like that described with micellar systems. This optimization diminishes the deleterious effects of bioactive compounds with short half lives. In addition, it permits a reduction in toxicity or synergize with the formulated drugs leading to a better treatment for the patient.
Many systems have been described to improve formulation of bioactive compounds. Among them are found colloidal drug delivery systems that are promising such as liposomes, microspheres, nanospheres and block copolymer micelles that increase the therapeutic index and improve the selectivity of various potent drugs (Gregoriadis G., (1995) TIBS, 13:527-537; Muller R. H., (1991) Colloidal Carriers for Controlled Drug Delivery and Targeting: Modification, Characterization and In vivo Distribution, CRC Press Inc., Florida; Kabanov A. V., Alakhov V. Y. (1997). “Micelles of Amphiphilic Block Copolymers as Vehicles for Drug Delivery” In Amphiphilic Block Copolymers: Self-Assembly and Applications edited by Alexamdris P., Lindman B., Elsevier, Netherlands; Kwon G. et al. (1997) J. Controlled Release, 48:195-201; La S. B. et al. (1996) Journal of Pharmaceutical Sciences, 85:85-90; Kataoka K. et al. (1992) J. Control. Release, 24:119-132). These vehicles optimize the therapeutic efficacy of drugs by preventing their rapid elimination from the body, reducing their systemic toxicity, delaying their degradation and optimizing their metabolism (Muller R. H. (1991) supra; Kabanov A. V., Alakhov V. Y. (1997) supra). In addition, they also provide for effective delivery of drugs to specific target sites (Muller R. H., (1991) supra) and aid in overcoming both transport limitations and defense mechanisms associated with the multi-drug resistance phenotype.
Various approaches have been developed to provide continuous delivery of various biologically active agents, and, although these have overcome some of the problems of delivering the agents, numerous problems remain such as the linearity of release, bioavailability, absorption, biocompatibility of the materials used and loading capacity.
It would be highly desirable to be provided with a natural biopolymers forming micelles, being easily and inexpensively produced, that are enabling the delivery of an active molecule to a patient.